Network management in a communications network often requires information relative to the operation of the network. In the case of fiber optic communications networks, it is often desirable to know the precise condition of the optical signals transmitted through an optical fiber to perform channel diagnostics and to control the operation of the network. For example, in an optical fiber used to transmit up to sixteen channels or optical signals, certain information about each optical signal as it is transmitted through the optical fiber is important to ensure that the underlying information of the signal is relayed accurately.
For example, the actual channel presence is an important factor. This is important, for example, to inform a network monitor that a discontinuity has been created that prevents a single channel or multiple channels from being transmitted through the optical fiber. In such a circumstance, a network monitor function may be implemented that routes optical signals around the faulty pathway until the discontinuity is remedied.
Also, the power of each channel is another important factor used to maintain channel equalization. Specifically, the power of the optical signal over a channel may be affected by many different factors inherent in the optical network. In the case of a single fiber, different channels may operate at different power levels a which is undesirable due to the periodical use of optical amplifiers in an optical network and due to other factors. Determining the actual power of the optical signals in an optical fiber for each channel is important in order to determine necessary adjustments in performing channel equalization functions. Other important information may include the noise density across the various channels in an optical fiber as well as any frequency shift experienced by a particular channel.